1. Field of the Invention
The present invention relates to a wet jigging machine for separating minerals such as coal, etc., in which a pulsation of the working liquid is generated by compressed air which is controlled by disk valves having shaft guidance.
2. Description of the Prior Art
Wet jigging machines for separating minerals and which are controlled by disk valves exhibit servo devices, preferably pneumatic servo devices, for the valve actuation in known embodiments in order to be able to execute the rapid opening and closing movements which are required, despite the size and weight of the disk valves. Given this type of valve actuation, the observance of precise opening and closing times and of identical valve opening characteristics is difficult. On the one hand, fluctuations of air pressure in the compressed air network of the mineral processing plants have an influence, and, on the other hand, for example, so do differences in the humidity or oil content of the compressed air. Therefore, expensive and complicated systems for cleaning the servo air and for maintaining its pressure constant are required.